|Abstract or Summary
- Rates of germination and emergence of corn were measured as
influenced by soil physical parameters using blotter paper and a sandy
loam soil as growth media. The corn seeds used were a hybrid of
Experimental conditions were soil temperature of 20°C, 25°C,
30°C, and 35°C, soil water potential of -33, -100, -500, and -1000
kPa, soil bulk density 1.29 and 1.36 Mg/m³ and seeding depth of 3 and
For the germination experiment seeds were put in contact with
polyethylene glycol at solution concentrations to produce the desired
water potentials. Treatment temperatures were maintained in a growth
chamber and germination was evaluated every twelve hours.
The number of hours required to obtain 50 and 80% germination was
significantly increased by lowering either temperature or water
potential. Although significant interactions were measured,
temperature and water potential affected germination in different ways. Time to attain 80% of germination decreased as temperature
increased until the optimum of 30°C was reached. Decreased osmotic
potential levels progressively delayed and reduced germination. Time
to germination increased greatly below -500 kPa.
For emergence experiments seeds were planted in soil packed in
covered containers which were placed in a growth chamber. Effects of
soil temperature, soil water potential, bulk density, and seeding
depth were evaluated. Bulk densities of 1.29 and 1.36 Mg/m³ , were
achieved by no compaction and compaction. The two seeding depth were
3 and 7 cm.
Time needed for emergence was influenced by soil temperature more
than by any other variable. The time for emergence decreased
progressively with lowering of soil water potential, lowering
temperature or with increase in seeding depth. No significant
differences resulted from increasing bulk density.
In both the germination and emergence experiments, changes in
temperature were more important than changes in water potential at
high water potential. However this relation was reversed at water
potentials lower than -500 kPa, where changes in water potential were
more important than changes in temperature. The minimum time for both
germination and emergence occurred at 30°C, at all water potentials.
Effect of seeding depth was more important than effect of bulk
density for time to emergence. Increases in time were between 20-30%
as the seeding depth increased from 3 to 7 cm.
Compaction began to limit seedling emergence at 1.44 Mg/m³.